1. Field of the Invention
This invention relates to information technology (IT), and more particularly, to a RAID capacity expansion handling method and system which is designed for use by a computer platform that is equipped with a disk array unit, such as a RAID (Redundant Array of Independent Disks) unit, for providing the RAID unit with a capacity expansion operation with concurrent data access capability that allows the RAID unit to be externally accessible by client stations during active runtime of the capacity expansion procedure.
2. Description of Related Art
RAID (Redundant Array of Independent Disks) is a multi-disk storage unit that contains two or more hard disks for providing a very large data storage capacity. A RAID unit is commonly connected to one or more servers in a network system for these servers to store the large amount of data that flow through the network system. Since a RAID unit contains multiple independent disks, it allows mirrored or interleaved data storage methods that can significantly enhance data access speed and also provide a multiple backup function that allows the storage of data to be highly reliable and secured.
In actual applications, the multiple disks of a RAID unit are grouped into one or more clusters, each cluster being used for serving a specific storage purpose, such as email server storage or file server storage. Presently, when the network management personnel wants to expand the total capacity of a certain disk cluster, a new disk cluster rather than a single disk should be added to the RAID unit.
One drawback to the above-mentioned practice, however, is that the newly-added disk cluster would have a different parity from the original disk cluster. This problem would considerably increase the complexity in data structure and programming, thus making the capacity expansion procedure difficult and complicated to realize.
Moreover, during active runtime of the capacity expansion procedure, it will inhibit the network server from gaining access to the RAID unit, i.e., the network server cannot read or write data on the RAID unit concurrently at the same time when the capacity expansion procedure is in active process. Therefore, when the capacity expansion procedure is running, the network server will temporarily halt its network services. This drawback will apparently degrade network system performance and serviceability.